Irene Urzaiz (イレーネ・ウルサイス) is a student of Rewolf Black Institute.
Irene has dark, shoulder-length hair. She wears the Rewolf Black Institute uniform and a scarf around her neck at all times. She has her uniformed unzipped to almost waist length and revealing her chest in a dark red undergarment. Irene also has two fanged teeth, due to the Gravisheath's influence, that enable her to suck blood from others to use for her Ogre Lux.
Irene is harsh, cynical, rude, and violent, which could be partially attributed to their harsh upbringing. As such, she irritates, and makes enemies easily out of, just about anyone around her. Priscilla seems to be the only one capable of telling her off, even capable of making her apologize to others for her misdeeds. Despite her harsh personality, she is also seen to be capable of some social interaction. Ayato notices that her and Julis, while arguing, also seem to have clear boundaries and very little hatred toward each other. He believes they were becoming friends in their own, rough way.
Despite so, she has proven herself to be honorable, insisting of properly returning Ayato's favor of saving Priscilla, before fighting him, going so far as to tell Ayato that she was ordered to kill him by Dirk. She is also respectful to opponents that meet her standards and impress her with their strength, such as Ayato, Julis, and Lester.
After Gravisheath was destroyed, she seems to have mellowed a bit, acknowledging Ayato's effort in saving her and thanking him.
When her younger sister's status as a Regenerative Strega was discovered, she was sold to Allekant by the sisters' parents. As a desperate effort to save her, Irene tried to escape with Priscilla. Three days after running away with her sister, Dirk Eberwein found the girls taking shelter in an abandoned building. He gave Irene the Gravisheath and upon her being compatible with it, he asked her for her wish. She wished for him to free Priscillia. Dirk Eberwein bought Priscilla from Allekant and promised her protection in exchange for Irene becoming his "pawn". The sum she owes him is incredibly large as she states she doesn't even know how many decades it would take to pay off while working a regular job. Under the rules of their agreement, Irene can only participate in the festas with Dirk's permission and she is not allowed to use her wish to pay him back if she wins. Dirk also makes it very clear that she works for him and not Le Wolfe.
Sometime before the series, Irene got into a fight at one of the illegal casinos and trashed it. Due to this, there are people from the casino looking to settle a score with her and she was also taken to the disciplinary area of Le Wolfe.
- Uno Fanega (単重壊): Irene swings the Gravisheath to create a single black gravity sphere in front of her that she launches at her opponent.
- Tres Fanega (三重壊): Irene swings the Gravisheath to create three purple spheres around her that she launches at her opponent. She also activates a gravity field during this move to prevent her opponent from dodging. If a sphere hits an opponent's weapon, it can swallow it and shrink, effectively destroying it in the process.
- Diez Fanega (十重壊): Irene swings the Gravisheath to create several black gravity spheres around her that she launches at her opponent.
- Diez Mil Fanega (万重壊): Irene swings the Gravisheath to create a countless number of gravity spheres around her that she launches at her opponent. These spheres are smaller than the others, being around the same size as a fist.
- Cien Guestia (百葬重列) Irene causes the Gravisheath to flash, creating a purple wave that is similar to an aurora. The wave crushes everything within it into nothing.
- Orreaga Pesado (重獄葦): Irene creates a purple jail bar wall made of elongated gravity spheres. According to Irene, this move is used to protect Priscilla and can't be easily destroyed.
Genestellar (星脈世代): As a Genestellar, Irene has enhanced physical ability and an aura known as prana.
- Superb Prana Control: After training under Xinglou, Irene became able to concentrate her prana in her hands and legs, allowing her to deal destructive blows or move at extremely high speed.
Skilled Fighter: Irene is skilled in close combat fighting, being able to stay at rank 18 even though the Gravisheath was destroyed. She improved greatly after her training.
The two are very close sisters, who are widely dependent on the other, as can be seen in their tag team fights. Irene sees it as her responsibility to protect Priscilla. Priscilla is also the only member of Irene's family whom she has any affection for.
- According to the author, Irene's birthday is December 6th, as that day is Sister's Day in Japan. In addition, her horoscope is Sagittarius, and her blood type is B.